Composition and method for polishing bulk silicon

ABSTRACT

The invention provides a polishing composition comprising (a) silica, (b) one or more compounds that increase the removal rate of silicon, (c) one or more tetraalkylammonium salts, and (d) water, wherein the polishing composition has a pH of about 7 to about 11. The invention further provides a method of polishing a substrate with the polishing composition.

CROSS-REFERENCE TO RELATED APPLICATION

This patent application is a continuation-in-part of copending U.S.patent application Ser. No. 12/462,638, filed Sep. 16, 2009.

BACKGROUND OF THE INVENTION

Silicon wafers used in electronic devices are typically prepared from asingle crystal silicon ingot that is first sliced into thin wafers usinga diamond saw, lapped to improve flatness, and etched to removesubsurface damage caused by lapping. The silicon wafers are thentypically polished in a two-step process to remove nanotopography causedby etching and to achieve the desired thickness before the wafers areacceptable for use in electronic devices.

In the first polishing step, a high removal rate is required, andideally the nanotopography would not be worsened during this step.Nanotopography is a parameter that measures the front-surface topologyof an area and is defined as the deviation of a surface within a spatialwavelength of around 0.2 to 20 mm. Nanotopography differs from surfaceflatness in that, for nanotopography, the flatness of the wafer surfaceis measured relative to the wafer surface itself, while for surfaceflatness, the flatness of the wafer surface is measured relative to aflat chuck used to hold the wafer. Thus, a wafer may have perfectflatness, yet still have nanotopography. If a wafer has surfaceirregularities on the front and back sides of the wafer, but the frontand back surfaces are parallel, the wafer has perfect flatness. However,the same wafer will exhibit nanotopography. Nanotopography bridges thegap between roughness and flatness in the topology map of wafer surfaceirregularities in spatial frequency.

Conventional polishing compositions for silicon wafers exhibit highremoval rates for silicon, but produce increased nanotopography of thesilicon wafers. The increased nanotopography puts increased demands onthe second, final polishing step to produce silicon wafers suitable forfurther processing into semiconductor substrates.

In addition, the edges of the silicon wafers can come into contact withprocessing apparatus and transporting cases, which can result incracking or chipping at the edge surfaces of the wafers. Fine particlescan be generated by the cracking or chipping, which can interfere withfurther processing. Contamination of the silicon wafers with very fineparticles can also occur at the coarsened surface of the edge, whichparticles can be released during processing and result in contaminationof the wafer surfaces. Thus, the outermost periphery edge of the waferis typically chamfered and then mirror polished at an early stage of thewafer processing. Further, in some processes, the silicon wafers areoxidized on one side to form a protective layer of silicon oxide, and sopart of the wafer edge comprises silicon oxide. While silicon polishingcompositions can be used for edge polishing, typically, a higher removalrate is needed for edge polishing of silicon wafers than for surfacepolishing. In addition, a suitable edge polishing composition desirablyexhibits a useful removal rate on silicon oxide as well as on silicon.Thus, there remains a need in the art for improved polishingcompositions for silicon wafers.

BRIEF SUMMARY OF THE INVENTION

The invention provides a polishing composition comprising (a) silica,(b) a compound or compounds that increases the removal rate of silicon,(c) a tetraalkylammonium salt, and (d) water, wherein the polishingcomposition has a pH of about 7 to about 11.

A first embodiment of the inventive chemical-mechanical polishingcomposition comprises a chemical mechanical polishing compositionconsisting essentially of or consisting of (a) about 0.5 wt. % to about20 wt % of silica, (b) about 0.01 wt. % to about 5 wt. % of one or moreorganic carboxylic acids, (c) about 0.0005 wt. % to about 2 wt. % of oneor more aminophosphonic acids, (d) about 0.01 wt. % to about 5 wt. % ofone or more tetraalkylammonium salts, (e) optionally one or morebicarbonate salts, (f) optionally potassium hydroxide, and (g) water,wherein the polishing composition has a pH of about 7 to about 11.

A second embodiment of the inventive chemical-mechanical polishingcomposition comprises a chemical mechanical polishing compositionconsisting essentially of or consisting of (a) about 0.5 wt. % to about20 wt. % of silica, (b) about 0.01 wt. % to about 2 wt. % of one or morepolyaminocarboxylic acids, (c) about 0.05 wt. % to about 5 wt. % of oneor more amines, (d) about 0.1 wt. % to about 5 wt. % of one or moretetraalkylammonium salts, (e) about 0.001 wt. % to about 1 wt. % of oneor more diol compounds, (I) optionally one or more bicarbonate salts,and (g) water, wherein the polishing composition has a pH of about 7 toabout 11.

A third embodiment of the inventive chemical-mechanical polishingcomposition comprises a chemical mechanical polishing compositionconsisting essentially of or consisting of (a) about 0.5 wt. % to about20 wt. % of silica, (b) about 0.01 wt. % to about 2 wt. % of one or morepolyaminocarboxylic acids, (c) about 0.1 wt. % to about 5 wt. % of oneor more tetraalkylammonium salts, (d) about 0.01 wt. % to about 5 wt. %of one or more organic carboxylic acids, (e) optionally about 0.1 wt. %to about 5 wt. % of one or more amines, (1) optionally one or morebicarbonate salts, and (g) water, wherein the polishing composition hasa pH of about 7 to about 11.

A fourth embodiment of the inventive chemical-mechanical polishingcomposition comprises a chemical mechanical polishing compositionconsisting essentially of or consisting of (a) about 0.5 wt. % to about20 wt. % of silica, (b) about 0.02 wt. % to about 5 wt. % of one or morenitrogen-containing heterocyclic compounds, (c) about 0.05 wt. % toabout 2 wt. % of one or more aminophosphonic acids, (d) about 0.1 wt. %to about 5 wt. % of one or more tetraalkylammonium salts, (e) optionallyone or more bicarbonate salts, and (0 water, wherein the polishingcomposition has a pH of about 7 to about 11.

The invention also provides a method for chemically-mechanicallypolishing a substrate with the inventive chemical-mechanical polishingcomposition.

A first embodiment of the inventive method for chemically-mechanicallypolishing a substrate comprises (i) contacting a substrate with apolishing pad and a chemical mechanical polishing composition consistingessentially of or consisting of (a) about 0.5 wt. % to about 20 wt. % ofsilica, (b) about 0.02 wt. % to about 5 wt. % of one or more organiccarboxylic acids, (c) about 0.02 wt. % to about 2 wt. % of one or moreaminophosphonic acids, (d) about 0.1 wt. % to about 5 wt. % of one ormore tetraalkylammonium salts, (e) optionally one or more bicarbonatesalts, (f) optionally potassium hydroxide, and (g) water, wherein thepolishing composition has a pH of about 7 to about 11, (ii) moving thepolishing pad relative to the substrate with the chemical-mechanicalpolishing composition therebetween, and (iii) abrading at least aportion of the substrate to polish the substrate.

A second embodiment of the inventive method for chemically-mechanicallypolishing a substrate comprises (i) contacting a substrate with apolishing pad and a chemical mechanical polishing composition consistingessentially of or consisting of (a) about 0.5 wt. % to about 20 wt. % ofsilica, (b) about 0.01 wt. % to about 2 wt. % of one or morepolyaminocarboxylic acids, (c) about 0.05 wt. % to about 5 wt. % of oneor more amines, (d) about 0.1 wt. % to about 5 wt. % of one or moretetraalkylammonium salts, (e) about 0.001 wt. % to about 1 wt. % of oneor more diol compounds, (f) optionally one or more bicarbonate salts,and (g) water, wherein the polishing composition has a pH of about 7 toabout 11, (ii) moving the polishing pad relative to the substrate withthe chemical-mechanical polishing composition therebetween, and (iii)abrading at least a portion of the substrate to polish the substrate.

A third embodiment of the inventive method for chemically-mechanicallypolishing a substrate comprises (i) contacting a substrate with apolishing pad and a chemical mechanical polishing composition consistingessentially of or consisting of (a) about 0.5 wt. % to about 20 wt. % ofsilica, (b) about 0.01 wt. % to about 2 wt. % of one or morepolyaminocarboxylic acids, (c) about 0.1 wt. % to about 5 wt % of one ormore tetraalkylammonium salts, (d) about 0.01 wt. % to about 5 wt. % ofone or more organic carboxylic acids, (e) optionally about 0.1 wt. % toabout 5 wt. % of one or more amines, (f) optionally one or morebicarbonate salts, and (g) water, wherein the polishing composition hasa pH of about 7 to about 11, (ii) moving the polishing pad relative tothe substrate with the chemical-mechanical polishing compositiontherebetween, and (iii) abrading at least a portion of the substrate topolish the substrate.

A fourth embodiment of the inventive method for chemically-mechanicallypolishing a substrate comprises (i) contacting a substrate with apolishing pad and a chemical mechanical polishing composition consistingessentially of or consisting of (a) about 0.5 wt. % to about 20 wt. % ofsilica, (b) about 0.02 wt. % to about 5 wt. % of one or morenitrogen-containing heterocyclic compounds, (c) about 0.05 wt. % toabout 2 wt. % of one or more aminophosphonic acids, (d) about 0.1 wt. %to about 5 wt. % of one or more tetraalkylammonium salts, (e) optionallyone or more bicarbonate salts, and (f) water, wherein the polishingcomposition has a pH of about 7 to about 11, (ii) moving the polishingpad relative to the substrate with the chemical-mechanical polishingcomposition therebetween, and (iii) abrading at least a portion of thesubstrate to polish the substrate.

The invention further provides a method for polishing an edge of asilicon wafer, wherein the edge consists essentially of silicon, whichmethod comprises (i) contacting a substrate with a polishing pad and achemical mechanical polishing composition consisting essentially of (a)about 0.5 wt. % to about 20 wt. % of wet process silica, (b) about 0.01wt. % to about 5 wt. % of an organic carboxylic acid, (c) about 0.0005wt. % to about 2 wt. % of an aminophosphonic acid, (d) about 0.01 wt. %to about 5 wt. % of a tetraalkylammonium salt, (e) potassium hydroxide,(f) optionally, a bicarbonate salt, and (g) water, wherein the polishingcomposition has a pH of about 7 to about 11, (ii) moving the polishingpad relative to the edge of the silicon wafer with the chemicalmechanical polishing composition therebetween, and (iii) abrading atleast a portion of the edge to polish the edge of the silicon wafer.

The invention additionally provides a method for polishing an edge of awafer, wherein the edge has a surface consisting essentially of siliconand silicon oxide, which method comprises (i) contacting a substratewith a polishing pad and a chemical mechanical polishing compositionconsisting essentially of (a) about 0.5 wt. % to about 20 wt. % ofsilica, (b) about 0.01 wt. % to about 5 wt. % of an organic carboxylicacid, (c) about 0.0005 wt. % to about 1 wt. % of an aminophosphonicacid, (d) about 0.01 wt. % to about 5 wt. % of a tetraalkylammoniumsalt, (e) optionally, a bicarbonate salt, (I) optionally, potassiumhydroxide, and (g) water, wherein the polishing composition has a pH ofabout 7 to about 11, (ii) moving the polishing pad relative to the edgeof the wafer with the chemical mechanical polishing compositiontherebetween, and (iii) abrading at least a portion of the edge topolish the edge of the wafer.

BRIEF DESCRIPTION OF THE DRAWING(S)

The FIGURE is a schematic drawing that illustrates the surface parameterR_(max).

DETAILED DESCRIPTION OF THE INVENTION

The invention provides a polishing composition comprising (a) silica,(b) a compound or compounds that increases the removal rate of silicon,(c) a tetraalkylammonium salt, and (d) water, wherein the polishingcomposition has a pH of about 7 to about 11.

The silica can be any suitable form of silica such as wet-process typesilica, fumed silica, or combinations thereof. For example, the silicacan comprise wet-process type silica particles (e.g.,condensation-polymerized or precipitated silica particles).Condensation-polymerized silica particles typically are prepared bycondensing Si(OH)₄ to form colloidal particles, where colloidalparticles are defined as having an average particle size between about 1nm and about 1000 nm. Such abrasive particles can be prepared inaccordance with U.S. Pat. No. 5,230,833 or can be obtained as any ofvarious commercially available products, such as the Akzo-Nobel Bindzil50/80 product, the Nalco DVSTS006 product, and the Fuso PL-2 product, aswell as other similar products available from DuPont, Bayer, AppliedResearch, Nissan Chemical, and Clariant.

The silica can comprise fumed silica particles. Fumed silica particlescan be produced from volatile precursors (e.g., silicon halides) in apyrogenic process by hydrolysis and/or oxidation of the precursors in ahigh temperature flame (H₂/air or H₂/CH₄/air) to produce the fumedsilica. The solution containing the precursor can be sprayed into a hightemperature flame using a droplet generator, and the metal oxide canthen be collected. Typical droplet generators include bi-fluidatomizers, high-pressure spray nozzles, and ultrasonic atomizers.Suitable fumed silica products are commercially available from producerssuch as Cabot, Tokuyama, and Degussa.

The silica can have any suitable average particle size (i.e., averageparticle diameter). The silica can have an average particle size ofabout 4 nm or more, e.g., about 10 nm or more, about 15 nm or more,about 20 nm or more, or about 25 nm or more. Alternatively, or inaddition, the silica can have an average particle size of about 180 nmor less, e.g., about 120 nm or less, about 110 nm or less, about 100 nmor less, about 90 nm or less, about 80 nm or less, about 70 nm or less,about 60 nm or less, 50 nm or less, or about 40 nm or less. Thus, thesilica can have an average particle size bounded by any two of the aboveendpoints. For example, the silica can have an average particle size ofabout 10 nm to about 100 nm, about 20 nm to about 100 nm, about 20 nm toabout 80 nm, about 20 nm to about 60 nm, or about 20 nm to about 40 nm.For a non-spherical silica particle, the size of the particle is thediameter of the smallest sphere that encompasses the particle.

The polishing composition can comprise any suitable amount of silica.Typically, the polishing composition can contain about 0.5 wt. % ormore, e.g., about 1 wt. % or more, about 2 wt. % or more, or about 5 wt.% or more of silica. Alternatively, or in addition, the polishingcomposition can contain about 20 wt. % or less, e.g., about 15 wt. % orless, about 10 wt. % or less, about 8 wt. % or less, about 6 wt. % orless, or about 5 wt. % or less of silica. Thus, the polishingcomposition can comprise silica in an amount bounded by any two of theabove endpoints recited for silica. For example the polishingcomposition can comprise about 0.5 wt. % to about 20 wt. %, about 1 wt.% to about 15 wt. %, about 5 wt. % to about 15 wt. %, or about 0.5 wt. %to about 5 wt. % of silica.

The silica particles preferably are colloidally stable. The term colloidrefers to the suspension of silica particles in the liquid carrier.Colloidal stability refers to the maintenance of that suspension throughtime. In the context of this invention, an abrasive is consideredcolloidally stable if, when the abrasive is placed into a 100 mlgraduated cylinder and allowed to stand unagitated for a time of 2hours, the difference between the concentration of particles in thebottom 50 ml of the graduated cylinder ([B] in terms of g/ml) and theconcentration of particles in the top 50 ml of the graduated cylinder([T] in terms of g/ml) divided by the initial concentration of particlesin the abrasive composition ([C] in terms of g/ml) is less than or equalto 0.5 (i.e., {[B]−[T]}/[C]≦0.5). More preferably, the value of[B]−[T]/[C] is less than or equal to 0.3, and most preferably is lessthan or equal to 0.1.

The polishing composition comprises water. The water is used tofacilitate the application of the abrasive particles, compound(s) thatincrease the removal rate of silicon, and any other additives to thesurface of a suitable substrate to be polished or planarized.Preferably, the water is deionized water.

The polishing composition has a pH of about 11 or less (e.g., about 10or less). Preferably, the polishing composition has a pH of about 7 ormore (e.g., about 8 or more). Even more preferably, the polishingcomposition has a pH of about 7 to about 11 (e.g., about 8 to about 10).The polishing composition optionally contains pH adjusting agents, forexample, potassium hydroxide, ammonium hydroxide, and/or nitric acid.The polishing composition also optionally comprises pH bufferingsystems. Many such pH buffering systems are well known in the art. ThepH buffering agent can be any suitable buffering agent, for example,bicarbonate-carbonate buffer systems, aminoalkylsulfonic acids, and thelike. The polishing composition can comprise any suitable amount of a pHadjustor and/or a pH buffering agent, provided that a suitable amount isused to achieve and/or maintain the pH of the polishing compositionwithin a suitable range.

A first embodiment of the inventive chemical-mechanical polishingcomposition provides a chemical mechanical polishing compositionconsisting essentially of or consisting of (a) about 0.5 wt. % to about20 wt. % of silica, (b) about 0.01 wt. % to about 5 wt. % of an organiccarboxylic acid, (c) about 0.0005 wt. % to about 2 wt. % of anaminophosphonic acid, (d) about 0.01 wt. % to about 5 wt. % of atetraalkylammonium salt, (e) optionally a bicarbonate salt, (1)optionally potassium hydroxide, and (g) water, wherein the polishingcomposition has a pH of about 7 to about 11

The polishing composition of the first embodiment contains one or moresuitable organic carboxylic acids or salts thereof. The organiccarboxylic acid can be an alkyl carboxylic acid or aryl carboxylic acidand can be optionally substituted with groups selected from the groupconsisting of C₁-C₁₂ alkyl, amino, substituted amino (e.g., methylamino,dimethylamino, and the like), hydroxyl, halogen, and combinationsthereof. Preferably, the organic carboxylic acid is a hydroxycarboxylicacid (e.g., an aliphatic hydroxycarboxylic acid or a hydroxybenzoicacid), an amino acid, an amino hydroxybenzoic acid, or a pyridinecarboxylic acid. Non-limiting examples of suitable hydroxycarboxylicacids include malonic acid, lactic acid, malic acid, tartaric acid,acetohydroxamic acid, glycolic acid, 2-hydroxybutyric acid, benzilicacid, salicylic acid, and 2,6-dihydroxybenzoic acid. Non-limitingexamples of suitable amino acids include glycine, alanine, proline,lysine, cysteine, leucine, aspartic acid, glutamic acid, and2-amino-4-thiazolacetic acid. Non-limiting examples of an aminohydroxybenzoic acid include 3-aminosalicylic acid and3-amino-4-hydroxybenoic acid. Non-limiting examples of pyridinecarboxylic acids include picolinic acid and nicotinic acid.

The polishing composition of the first embodiment can contain anysuitable amount of the organic carboxylic acid(s). The polishingcomposition can contain about 0.01 wt. % or more, e.g., about 0.02 wt. %or more, e.g., about 0.05 wt. % or more, about 0.1 wt. % or more, orabout 0.5 wt. % or more of the organic carboxylic acid(s).Alternatively, or in addition, the polishing composition can containabout 5 wt. % or less, e.g., about 4 wt. % or less, about 3 wt. % orless, about 2 wt. % or less, or about 1 wt. % or less of the organiccarboxylic acid(s). Thus, the polishing composition can comprise theorganic carboxylic acid(s) in an amount bounded by any two of the aboveendpoints recited for the organic carboxylic acid(s). For example thepolishing composition can comprise about 0.01 wt. % to about 5 wt. %,0.02 wt. % to about 5 wt. %, 0.05 wt. % to about 4 wt. %, or about 0.1wt. % to about 3 wt. % of the organic carboxylic acid(s).

The polishing composition of the first embodiment contains one or moresuitable aminophosphonic acids. Preferably, the aminophosphonic acid isselected from the group consisting of ethylenediaminetetra(methylenephosphonic acid), amino tri(methylene phosphonic acid),diethylenetriaminepenta(methylene phosphonic acid), salts thereof, andcombinations thereof. More preferably, the aminophosphonic acid is aminotri(methylene phosphonic acid).

The polishing composition of the first embodiment can contain anysuitable amount of the aminophosphonic acid(s). Typically, the polishingcomposition can contain about 0.0005 wt. % or more, e.g., about 0.001wt. % or more, about 0.01 wt. % or more, about 0.02 wt. % or more, about0.05 wt. % or more, about 0.1 wt. % or more, about 0.2 wt. % or more, orabout 0.5 wt. % or more of the aminophosphonic acid(s). Alternatively,or in addition, the polishing composition can contain about 2 wt. % orless, e.g., about 1.5 wt. % or less, or about 1 wt. % or less of theaminophosphonic acid(s). Thus, the polishing composition can comprisethe aminophosphonic acid(s) in an amount bounded by any two of the aboveendpoints recited for the aminophosphonic acid(s). For example thepolishing composition can comprise about 0.0005 wt. % to about 2 wt. %,about 0.02 wt. % to about 2 wt. %, about 0.05 wt. % to about 2 wt. %,about 0.1 wt. % to about 1.5 wt. %, or about 0.5 wt. % to about 1 wt. %of the aminophosphonic acid(s).

The polishing composition of the first embodiment comprises one or moresuitable tetraalkylammonium salt(s). The tetraalkylammonium saltpreferably comprises a cation selected from the group consisting oftetramethylammonium, tetraethylammonium, tetrapropylammonium, andtetrabutylammonium. The tetraalkylammonium salt can have any suitablecation including but not limited to hydroxide, chloride, bromide,sulfate, or hydrogensulfate. In an embodiment, the tetraalkylammoniumsalt is a tetraalkylammonium hydroxide (e.g., tetramethylammoniumhydroxide).

The polishing composition of the first embodiment can comprise anysuitable amount of the tetraalkylammonium salt(s). Typically, thepolishing composition can contain about 0.01 wt. % or more, e.g., about0.1 wt. % or more, about 0.2 wt. % or more, or about 0.5 wt. % or moreof the tetraalkylammonium salt(s). Alternatively, or in addition, thepolishing composition can contain about 5 wt. % or less, e.g., about 4wt. % or less, about 3 wt. % or less, about 2 wt. % or less, or about 1wt. % or less of the tetraalkylammonium salt(s). Thus, the polishingcomposition can comprise the tetraalkylammonium salt(s) in an amountbounded by any two of the above endpoints recited for thetetraalkylammonium salt(s). For example the polishing composition cancomprise about 0.01 wt. % to about 5 wt. %, about 0.1 wt. % to about 5wt. %, about 0.2 wt. % to about 4 wt. %, or about 0.5 wt. % to about 3wt. % of the tetraalkylammonium salt(s).

In an embodiment, the polishing composition consists essentially of (a)about 0.5 wt. % to about 20 wt. % of wet process silica, (b) about 0.01wt. % to about 5 wt. % of an organic carboxylic acid selected from thegroup consisting of lactic acid, oxalic acid, 2-hydroxybutyric acid,benzilic acid, and combinations thereof, (c) about 0.0005 wt. % to about2 wt. % of an aminophosphonic acid selected from the group consisting ofethylenediaminetetra(methylene phosphonic acid), amino tri(methylenephosphonic acid), diethylenetriaminepenta(methylene phosphonic acid),and combinations thereof, (d) about 0.01 wt. % to about 5 wt. % of atetraalkylammonium hydroxide, (e) about 0.05 wt. % to about 2 wt. % ofpotassium hydroxide, (f) about 0.05 wt. % to about 5 wt. % of potassiumbicarbonate, and (g) water.

A second embodiment of the inventive chemical-mechanical polishingcomposition provides a chemical mechanical polishing compositionconsisting essentially of or consisting of (a) about 0.5 wt. % to about20 wt. % of silica, (b) about 0.01 wt. % to about 2 wt. % of apolyaminocarboxylic acid, (c) about 0.1 wt. % to about 5 wt. % of anamine, (d) about 0.1 wt. % to about 5 wt. % of a tetraalkylammoniumsalt, (e) about 0.001 wt. % to about 1 wt. % of a diol compound, (f)optionally a bicarbonate salt, and (g) water, wherein the polishingcomposition has a pH of about 7 to about 11.

The polishing composition of the second embodiment comprises one or moresuitable polyaminocarboxylic acids. The term polyaminocarboxylic acid asused herein refers to a compound having two or more amino groups and twoor more carboxylic acid groups. Preferably, the polyaminocarboxylic acidis selected from the group consisting of ethylenediaminetetraaceticacid, diethylenetriaminepentaacetic acid,N-(hydroxyethyl)ethylenediaminetriacetic acid, nitrilotriacetic acid,methylglycinediacetic acid, salts thereof, and combinations thereof.More preferably, the polyaminocarboxylic acid is selected from the groupconsisting of ethylenediaminetetraacetic acid or a salt thereof (e.g., amono-, di-, tri-, or tetrasodium salt thereof).

The polishing composition of the second embodiment can comprise anysuitable amount of the polyaminocarboxylic acid(s). Typically, thepolishing composition can contain about 0.01 wt. % or more, e.g., about0.1 wt. % or more, about 0.2 wt. % or more, or about 0.5 wt. % or moreof the polyaminocarboxylic acid(s). Alternatively, or in addition, thepolishing composition can contain about 2 wt. % or less, e.g., about 1.5wt. % or less, or about 1.0 wt. % or less of the polyaminocarboxylicacid(s). Thus, the polishing composition can comprise thepolyaminocarboxylic acid(s) in an amount bounded by any two of the aboveendpoints recited for the polyaminocarboxylic acid(s). For example thepolishing composition can comprise about 0.01 wt. % to about 2 wt. %,0.1 wt. % to about 1.5 wt. %, or about 0.5 wt. % to about 1 wt. % of thepolyaminocarboxylic acid(s).

The polishing composition of the second embodiment comprises one or moresuitable amines. Non-limiting examples of suitable amines includepiperazine, aminoethylpiperazine, 2-methyl-2-aminoethanol,(2-aminoethyl)-2-aminoethanol, ethanolamine, diethanolamine,triethanolamine, ethylenediamine, diethylenetriamine,tetraethylenepentamine, hydrazine, 2-hydroxyethylhydrazine,semicarbazide, hydroxylamine, N-methylhydroxylamine,O-methylhydroxylamine, and O-carboxymethylhydroxylamine. Morepreferably, the amine is piperazine or aminoethylpiperazine.

The polishing composition of the second embodiment can comprise anysuitable amount of the amine(s). Typically, the polishing compositioncan contain about 0.05 wt. % or more, e.g., about 0.1 wt. % or more,about 0.2 wt. % or more, or about 0.5 wt. % or more of the amine(s).Alternatively, or in addition, the polishing composition can containabout 5 wt. % or less, e.g., about 4 wt. % or less, about 3 wt. % orless, about 2 wt. % or less, or about 1 wt. % or less of the amine(s).Thus, the polishing composition can comprise the amines) in an amountbounded by any two of the above endpoints recited for the amine(s). Forexample the polishing composition can comprise about 0.05 wt. % to about5 wt. %, 0.2 wt. % to about 4 wt. %, or about 0.5 wt. % to about 3 wt. %of the amine(s).

The polishing composition of the second embodiment comprises one or moresuitable tetraalkylammonium salts. The tetraalkylammonium salt andamount thereof can be as recited for the first embodiment of thepolishing composition.

The polishing composition of the second embodiment comprises one or moresuitable diol compounds. The diol compound can be any suitable diolcompound and typically is a 1,2-diol compound or a 1,3-diol compound.Typically, the diol compound is a linear or branched-chain C₂-C₁₀ diolcompound. Non-limiting examples of suitable 1,2-diol compounds include1,2-propane diol, 1,2-butane diol, 1,2-pentane diol, 2,3-pentane diol,and combinations thereof. Non-limiting examples of suitable 1,3-diolcompounds include 1,3-propane diol, 1,3-butane diol, 1,3-pentane diol,2,4-pentane diol, and combinations thereof.

The polishing composition of the second embodiment can comprise anysuitable amount of the diol compound(s). Typically, the polishingcomposition can contain about 0.001 wt. % or more, e.g., about 0.005 wt.% or more, about 0.01 wt. % or more, or about 0.05 wt. % or more of thediol compound(s). Alternatively, or in addition, the polishingcomposition can contain about 1 wt. % or less, e.g., about 0.75 wt. % orless, about 0.5 wt. % or less, about 0.25 wt. % or less, or about 0.1wt. % or less of the diol compound(s). Thus, the polishing compositioncan comprise the diol compound(s) in an amount bounded by any two of theabove endpoints recited for the diol compound(s). For example thepolishing composition can comprise about 0.001 wt. % to about 1 wt. %,0.005 wt. % to about 0.75 wt. %, or about 0.01 wt. % to about 0.5 wt. %of the diol compound(s).

A third embodiment of the inventive chemical-mechanical polishingcomposition comprises a chemical mechanical polishing compositionconsisting essentially of or consisting of (a) about 0.5 wt. % to about20 wt. % of silica, (b) about 0.01 wt. % to about 2 wt. % of apolyaminocarboxylic acid, (c) about 0.1 wt. % to about 5 wt. % of atetraalkylammonium salt, (d) about 0.1 wt. % to about 5 wt. % of anorganic carboxylic acid, (e) optionally about 0.1 wt. % to about 5 wt. %of an amine, (1) optionally a bicarbonate salt, and (g) water, whereinthe polishing composition has a pH of about 7 to about 11. Thepolyaminocarboxylic acid, tetraalkylammonium salt, organic carboxylicacid, amine, and amounts thereof contained in the third embodiment ofthe inventive chemical-mechanical polishing composition can be asrecited herein for the first and second embodiments of the inventivepolishing composition.

A fourth embodiment of the inventive chemical-mechanical polishingcomposition provides a chemical mechanical polishing compositionconsisting essentially of or consisting of (a) about 0.5 wt. % to about20 wt. % of silica, (b) about 0.02 wt. % to about 5 wt. % of anitrogen-containing heterocyclic compound, (c) about 0.05 wt. % to about2 wt. % of an aminophosphonic acid, (d) about 0.1 wt. % to about 5 wt. %of a tetraalkylammonium salt, (e) optionally a bicarbonate salt, and (f)water, wherein the polishing composition has a pH of about 7 to about11. The aminophosphonic acid, tetraalkylammonium salt, and amountsthereof contained in the fourth embodiment of the inventivechemical-mechanical polishing composition can be as recited herein forthe first embodiment of the inventive polishing composition.

The polishing composition of the fourth embodiment comprises one or moresuitable nitrogen-containing heterocyclic compounds. The termnitrogen-containing heterocyclic compound as used herein refers to a 5-,6-, or 7-membered ring compound having one or more nitrogen atomscontained as part of the ring system. In an embodiment, thenitrogen-containing heterocyclic compound is a triazole. In a preferredembodiment, the nitrogen-containing heterocyclic compound is anaminotriazole. Non-limiting examples of suitable aminotriazoles include3-amino-1,2,4-triazole, 3-amino-1,2,4-triazole-5-carboxylic acid,3-amino-5-mercapto-1,2,4-triazole, and4-amino-5-hydrazino-1,2,4-triazole-3-thiol. In another embodiment, thenitrogen-containing heterocyclic compound is a thiazole. Non-limitingexamples of suitable thiazoles include 2-amino-5-methylthiazole,2-amino-4-thoazoleacetic acid, and thiazole. In another embodiment, thenitrogen-containing heterocyclic compound is a heterocyclic N-oxide.Non-limiting examples of suitable heterocyclic N-oxides include2-hydroxypyridine-N-oxide, 4-methylmorpholine-N-oxide, and picolinicacid N-oxide.

The polishing composition of the fourth embodiment can comprise anysuitable amount of the nitrogen-containing heterocyclic compound. Thepolishing composition can contain about 0.02 wt. % or more, e.g., about0.05 wt. % or more, about 0.1 wt. % or more, or about 0.5 wt. % or moreof the nitrogen-containing heterocyclic compound(s). Alternatively, orin addition, the polishing composition can contain about 5 wt. % orless, e.g., about 4 wt. % or less, about 3 wt. % or less, about 2 wt. %or less, or about 1 wt. % or less of the nitrogen-containingheterocyclic compound(s). Thus, the polishing composition can comprisethe nitrogen-containing heterocyclic compound(s) in an amount bounded byany two of the above endpoints recited for the nitrogen-containingheterocyclic compound(s). For example the polishing composition cancomprise about 0.02 wt. % to about 5 wt. %, 0.05 wt. % to about 4 wt. %,or about 0.1 wt. % to about 3 wt. % of the nitrogen-containingheterocyclic compound(s).

The polishing composition optionally further contains one or morebicarbonate salts. The bicarbonate salt can be any suitable bicarbonatesalt and can be, for example, potassium bicarbonate, sodium bicarbonate,ammonium bicarbonate, or combinations thereof.

The polishing composition can contain any suitable amount of thebicarbonate salt(s). Typically, the polishing composition can containabout 0.05 wt. % or more, e.g., about 0.1 wt. % or more, about 0.25 wt.% or more, or about 0.5 wt. % or more of the bicarbonate salt(s).Alternatively, or in addition, the polishing composition can containabout 5 wt. % or less, e.g., about 4 wt. % or less, about 3 wt. % orless, about 2 wt. % or less, or about 1 wt. % or less of the bicarbonatesalt(s). Thus, the polishing composition can comprise the bicarbonatesalt(s) in an amount bounded by any two of the above endpoints recitedfor the bicarbonate salt(s). For example the polishing composition cancomprise about 0.05 wt. % to about 1 wt. %, 0.1 wt. % to about 4 wt. %,about 0.25 wt. % to about 3 wt. %, or about 0.5 wt. % to about 2 wt. %of the bicarbonate salt(s).

The polishing composition optionally further contains potassiumhydroxide. The polishing composition can contain any suitable amount ofpotassium hydroxide. Typically, the polishing composition can containabout 0.05 wt. % or more, e.g., about 0.1 wt. % or more, or about 0.25wt. % or more of potassium hydroxide. Alternatively, or in addition, thepolishing composition can contain about 2 wt. % or less, e.g., about 1.5wt. % or less, about 1 wt. % or less, about 0.8 wt. % or less, or about0.6 wt. % or less of potassium hydroxide. Thus, the polishingcomposition can comprise potassium hydroxide in an amount bounded by anytwo of the above endpoints recited for potassium hydroxide. For examplethe polishing composition can comprise about 0.05 wt. % to about 1 wt.%, 0.1 wt. % to about 2 wt. %, about 0.1 wt. % to about 1 wt. %, orabout 0.25 wt. % to about 0.8 wt. % of potassium hydroxide.

The polishing composition optionally further comprises one or more otheradditives. Such additives include any suitable dispersing agent, suchas, for example, homopolymers or random, block, or gradient acrylatecopolymers comprising one or more acrylic monomers (e.g., polyacrylates,polymethacrylates, vinyl acrylates and styrene acrylates), combinationsthereof, and salts thereof. Other suitable additives include biocides.The biocide can be any suitable biocide, for example, an isothiazolinonebiocide.

The polishing composition of the invention can be prepared by anysuitable technique, many of which are known to those skilled in the art.The polishing composition can be prepared in a batch or continuousprocess. Generally, the polishing composition can be prepared bycombining the components thereof in any order. The term “component” asused herein includes individual ingredients (e.g., silica, compound(s)that increases the removal rate of silicon, tetraalkylammonium salt,etc.) as well as any combination of ingredients (e.g., silica,compound(s) that increases the removal rate of silicon,tetraalkylammonium salt, buffers, etc.).

For example, in one embodiment, the silica can be dispersed in water.The organic carboxylic acid, aminophosphonic acid, andtetraalkylammonium salt can then be added, and mixed by any method thatis capable of incorporating the components into the polishingcomposition. Other compounds that increase the removal rate of siliconsimilarly can be utilized in the preparation of the polishingcomposition. The polishing composition can be prepared prior to use,with one or more components, such as a pH adjusting component, added tothe polishing composition just before use (e.g., within about 7 daysbefore use, or within about 1 hour before use, or within about 1 minutebefore use). The polishing composition also can be prepared by mixingthe components at the surface of the substrate during the polishingoperation.

The polishing composition also can be provided as a concentrate which isintended to be diluted with an appropriate amount of water prior to use.In such an embodiment, the polishing composition concentrate cancomprise, for example, silica, a compound or compounds that increasesthe removal rate of silicon, a tetraalkylammonium salt, and water inamounts such that, upon dilution of the concentrate with an appropriateamount of water, each component of the polishing composition will bepresent in the polishing composition in an amount within the appropriaterange recited above for each component. For example, the abrasive,compound or compounds that increases the removal rate of silicon, andtetraalkylammonium salt can each be present in the concentrate in anamount that is about 2 times (e.g., about 3 times, about 4 times, about5 times, about 10 times, or about 15 times) greater than theconcentration recited above for each component so that, when theconcentrate is diluted with an equal volume of water (e.g., 2 equalvolumes water, 3 equal volumes of water, 4 equal volumes of water, 9equal volumes of water, or 14 equal volumes of water, respectively),each component will be present in the polishing composition in an amountwithin the ranges set forth above for each component. Furthermore, aswill be understood by those of ordinary skill in the art, theconcentrate can contain an appropriate fraction of the water present inthe final polishing composition in order to ensure that the compound orcompounds that increases the removal rate of silicon, and other suitableadditives are at least partially or fully dissolved in the concentrate.

The invention further provides a method of chemically-mechanicallypolishing a substrate comprising (i) contacting a substrate with apolishing pad and the polishing composition described herein, (ii)moving the polishing pad relative to the substrate with the polishingcomposition therebetween, and (iii) abrading at least a portion of thesubstrate to polish the substrate.

Although the polishing composition of the invention can be used topolish any substrate, the polishing composition is particularly usefulin the polishing of a substrate comprising silicon, for example, siliconwafers used in the electronics industry. In this regard, the silicon canbe undoped silicon, or it can be doped silicon, such as p-type silicondoped with boron or aluminum. In addition, the silicon can bepolysilicon. The inventive polishing composition and method of usethereof is suitable for the pre-polishing or the final polishing ofsilicon wafers as produced from silicon single crystals by diamondsawing and rough grinding, as well as for edge polishing of siliconwafers and for use in the reclamation of silicon wafers by polishing.

Advantageously, the inventive polishing method exhibits improvednanotopography when used to polish silicon wafers after lapping andetching of diamond sawed silicon wafers. One way to measure change innanotopography during chemical-mechanical polishing is to determine thevalue of the parameter: ΔR_(z)/d wherein R_(z) is the average maximumheight of the profile, ΔR_(z) is the change in R_(z) from one time pointto another time point, e.g., before and after chemical-mechanicalpolishing, and d is the amount of material removed in microns over thatsame time span, with the result expressed in nanometers. Referring tothe FIGURE, R_(max) represents the largest peak to valley height in agiven sampling length L, and R_(z) represents the average of 5 R_(max)values in 5 contiguous sampling lengths. Sampling length L isapproximately 5 mm. Suitable techniques for measuring R_(max) (to enablethe calculation of R_(z)) include stylus profilometry, opticalprofilometry, and atomic force microscopy. Suitable instruments forstylus profilometry and optical profilometry are available from, e.g.,Veeco Instruments (Plainview, N.Y.). Desirably, the inventive polishingmethod results in a ΔR_(z)/d that is about zero or less, that is,substrate nanotopography is either unchanged or improved after use ofthe inventive polishing method.

The polishing method of the invention is particularly suited for use inconjunction with a chemical-mechanical polishing apparatus. Typically,the apparatus comprises a platen, which, when in use, is in motion andhas a velocity that results from orbital, linear, or circular motion, apolishing pad in contact with the platen and moving with the platen whenin motion, and a carrier that holds a substrate to be polished bycontacting and moving the substrate relative to the surface of thepolishing pad. The polishing of the substrate takes place by thesubstrate being placed in contact with the polishing pad and thepolishing composition of the invention and then the polishing pad movingrelative to the substrate, so as to abrade at least a portion of thesubstrate to polish the substrate.

A substrate can be polished with the chemical-mechanical polishingcomposition with any suitable polishing pad (e.g., polishing surface).Suitable polishing pads include, for example, woven and non-wovenpolishing pads. Moreover, suitable polishing pads can comprise anysuitable polymer of varying density, hardness, thickness,compressibility, ability to rebound upon compression, and compressionmodulus. Suitable polymers include, for example, polyvinylchloride,polyvinylfluoride, nylon, fluorocarbon, polycarbonate, polyester,polyacrylate, polyether, polyethylene, polyimide, polyurethane,polystyrene, polypropylene, conformed products thereof, and mixturesthereof. Hard polyurethane polishing pads are particularly useful inconjunction with the inventive polishing method.

Desirably, the chemical-mechanical polishing apparatus further comprisesan in situ polishing endpoint detection system, many of which are knownin the art. Techniques for inspecting and monitoring the polishingprocess by analyzing light or other radiation reflected from a surfaceof the substrate being polished are known in the art. Such methods aredescribed, for example, in U.S. Pat. No. 5,196,353, U.S. Pat. No.5,433,651, U.S. Pat. No. 5,609,511, U.S. Pat. No. 5,643,046, U.S. Pat.No. 5,658,183, U.S. Pat. No. 5,730,642, U.S. Pat. No. 5,838,447, U.S.Pat. No. 5,872,633, U.S. Pat. No. 5,893,796, U.S. Pat. No. 5,949,927,and U.S. Pat. No. 5,964,643. Desirably, the inspection or monitoring ofthe progress of the polishing process with respect to a substrate beingpolished enables the determination of the polishing end-point, i.e., thedetermination of when to terminate the polishing process with respect toa particular substrate.

In an embodiment, the inventive method provides a method for polishingan edge of a silicon wafer, wherein the edge consists essentially ofsilicon. In another embodiment, the inventive method provides a methodfor polishing an edge of a wafer, wherein the edge has a surfaceconsisting essentially of silicon and silicon oxide. The edge polishingcan be carried out using techniques that are well known in the art. Forexample, edge polishing can be performed using edge polishers suppliedby SpeedFam Co., Ltd., Kanagawa, Japan.

Advantageously, the inventive polishing method exhibits improvedchucking mark performance when used to polish the edges of siliconwafers, wherein the edges of the silicon wafers consist essentially ofsilicon or consist essentially of silicon and silicon oxide. In edgepolishing, the silicon wafers are typically held in place using a vacuumchuck attached to the back side of the wafer. The vacuum often drawspolishing compositions onto the back of the wafer during polishing,where it can dry. The dried residue is referred to as a chucking mark.If the residue resulting from drying of the polishing compositions isnot easily removed, the wafers then require additional cleaning stepsafter polishing, thereby adding to the cost of manufacture. Desirably,the inventive method results in chucking marks which are dry whiteresidues and easily removed during further processing of the wafers.

Advantageously, the inventive method further provides improved removalrates when used to polish wafers edges consisting essentially ofsilicon, thereby improving production throughput of the wafers. Inaddition, when used to polish wafers consisting essentially of siliconand silicon oxide, the inventive method exhibits improved removal ratesfor silicon oxide relative to silicon, thereby resulting in evenpolishing of the wafer edges.

The following examples further illustrate the invention but, of course,should not be construed as in any way limiting its scope.

Example 1

This example demonstrates the effect of an organic carboxylic acid, anaminophosphonic acid, and a tetraalkylammonium salt on the removal rateand surface roughness observed for silicon substrates achievable by thepolishing composition of the invention.

Seven similar substrates, which substrates comprised 102 cm (4 inch)diameter circular silicon wafers, were polished with seven differentpolishing compositions (Polishing Compositions 1A-1G). All of thepolishing compositions contained 1 wt. % silica wet-process silica(Polishing Compositions 1A, 1B, 1D, and 1F) or fumed silica (PolishingCompositions 1C, 1E, and 1G), 0.27 wt. % tetramethylammonium hydroxide,and 0.05 wt. % potassium bicarbonate in water at a pH of about 10.5.Polishing Composition 1A (comparative) further contained 0.017 wt. %ethylenediaminetetraacetic acid and 0.067 wt. % piperazine. PolishingCompositions 1B-1G further contained 0.033 wt. %diethylenetriaminepenta(methylene phosphonic acid) and an organiccarboxylic acid, which was either 0.08 wt. % malonic acid (PolishingCompositions 1B and 1C), 0.067 wt. % lactic acid (Polishing Compositions1D and 1E), or 0.107 wt. % malic acid (Polishing Compositions 1F and1G).

Following polishing, the removal rates for silicon and the magnitude ofthe change in nanotopography, ΔR_(z)/d, were determined for each of thepolishing compositions. The results are summarized in Table 1.

TABLE 1 Polishing Composition Silicon Removal Rate (Å/min) ΔR_(z)/d (nm)1A (comparative) 6500 6 1B (invention) 5700 0 1C (invention) 5200 0.1 1D(invention) 5150 0.4 1E (invention) 5650 0.4 1F (invention) 5700 −0.2 1G(invention) 5400 0

As is apparent from the results set forth in Table 1, the inventivepolishing compositions exhibited silicon removal rates that wereapproximately 79% to about 88% of the removal rate exhibited by thecomparative polishing composition, yet the inventive polishingcompositions exhibited a change in surface roughness caused by polishingthat ranged from a decrease in surface roughness of approximately 0.2 nm(Polishing Composition 1F) to an increase in surface roughness ofapproximately 0.4 nm (Polishing Compositions 1D and 1E), while thecomparative polishing composition exhibited an increase in surfaceroughness of approximately 6 nm.

Example 2

This example demonstrates the effect of an organic carboxylic acid, apolyaminocarboxylic acid, and a tetraalkylammonium salt on the removalrate and surface roughness observed for silicon substrates achievable bythe polishing composition of the invention.

Three similar substrates, which substrates comprised 102 cm (4 inch)diameter circular silicon wafers, were polished with three differentpolishing compositions (Polishing Compositions 2A-2C). PolishingComposition 2A (comparative) contained 1 wt. % wet-process silica,0.0167 wt. % ethylenediaminetetraacetic acid, 0.067 wt % piperazine,0.27 wt. % tetramethylammonium hydroxide, and 0.05 wt. % potassiumbicarbonate. Polishing Composition 2B (invention) contained 0.85 wt. %wet-process silica, 0.02 wt. % ethylenediaminetetraacetic acid, 0.083wt. % oxalic acid, 0.2 wt. % tetramethylammonium hydroxide, and 0.1 wt.% potassium bicarbonate. Polishing Composition 2C (invention) contained0.53 wt % wet-process silica, 0.0167 wt. % ethylenediaminetetraaceticacid, 0.007 wt. % oxalic acid, 0.067 wt. % tetramethylammoniumhydroxide, and 0.05 wt. % potassium bicarbonate.

Following polishing, the removal rates for silicon and the magnitude ofthe change in nanotopography, ΔR_(z)/d, were determined for each of thepolishing compositions. The results are summarized in Table 2.

TABLE 2 Polishing Composition Silicon Removal Rate (Å/min) ΔR_(z)/d (nm)2A 6700 4 2B 5900 −4 2C 5500 −7

As is apparent from the results set forth in Table 2, the inventivepolishing compositions exhibited silicon removal rates that wereapproximately 82% to about 88% of the removal rate exhibited by thecomparative polishing composition, yet the inventive polishingcompositions exhibited a decrease in surface roughness caused bypolishing of approximately 4 nm and 7 nm, as compared to an increase insurface roughness caused by polishing with the comparative polishingcomposition of approximately 4 nm.

Example 3

This example demonstrates the effect of an organic carboxylic acid, apolyaminocarboxylic acid, an amine, and a tetraalkylammonitun salt onthe removal rate and surface roughness observed for silicon substratesachievable by the polishing composition of the invention.

Two similar substrates, which substrates comprised 102 cm (4 inch)diameter circular silicon wafers, were polished with two differentpolishing compositions (Polishing Compositions 3A and 3B). PolishingCompositions 3A and 3B contained 1 wt. % wet-process silica, 0.0167 wt.% ethylenediaminetetraacetic acid, 0.067 wt. % piperazine, 0.27 wt. %tetramethylammonium hydroxide, and 0.05 wt. % potassium bicarbonate.Polishing Composition 3B (invention) further contained 0.033 wt. %benzilic acid.

Following polishing, the removal rates for silicon and the magnitude ofthe change in nanotopography, ΔR_(z)/d, were determined for each of thepolishing compositions. The results are summarized in Table 2.

TABLE 3 Polishing Composition Silicon Removal Rate (Å/min) ΔR_(z)/d (nm)3A 6250 6 3B 2550 −6

As is apparent from the results set forth in Table 3, the inventivepolishing composition exhibited a silicon removal rate that wasapproximately 42% of the removal rate exhibited by the comparativepolishing composition, yet the inventive polishing composition exhibiteda decrease in surface roughness caused by polishing of approximately 6nm as compared to an increase in surface roughness caused by polishingwith the comparative polishing composition of approximately 6 nm.

Example 4

This example demonstrates the effect of a diol compound, apolyaminocarboxylic acid, an amine, and a tetraalkylammonium salt on theremoval rate and surface roughness observed for silicon substratesachievable by the polishing composition of the invention.

Two similar substrates, which substrates comprised 102 cm (4 inch)diameter circular silicon wafers, were polished with two differentpolishing compositions (Polishing Compositions 4A and 4B). PolishingCompositions 4A and 4B contained 1 wt. % wet-process silica, 0.0167 wt.% ethylenediaminetetraacetic acid, 0.067 wt. % piperazine, 0.27 wt %tetramethylammonium hydroxide, and 0.05 wt. % potassium bicarbonate.Polishing Composition 3B (invention) further contained 0.033 wt. %2,4-pentanediol (i.e., a diol compound).

Following polishing, the removal rates for silicon and the magnitude ofthe change in nanotopography, ΔR_(z)/d, were determined for each of thepolishing compositions. The results are summarized in Table 4.

TABLE 4 Polishing Composition Silicon Removal Rale (Å/min) ΔR_(z)/d (nm)4A (comparative) 5350 −0.5 4B (invention) 4375 −5

As is apparent from the results set forth in Table 4, the inventivepolishing composition exhibited a silicon removal rate that wasapproximately 82% of the removal rate exhibited by the comparativepolishing composition, yet the inventive polishing composition exhibiteda decrease in surface roughness caused by polishing of approximately 5nm as compared to a decrease in surface roughness caused by polishingwith the comparative polishing composition of approximately −0.5 nm.

Example 5

This example demonstrates the chucking mark performance of an embodimentof the invention.

Two separate substrates, which substrates comprised sheets of polyvinylchloride (“PVC”) were misted with two different polishing compositions(Polishing Compositions 5A and 5B). Polishing Composition 5A(comparative) contained 0.04 wt. % of an aminophosphonic acid, 0.2 wt. %of tetramethylammonium hydroxide, 0.1 wt. % of potassium bicarbonate,0.044 wt. % of oxalic acid, and 0.85 wt. % of a wet-process silica.Polishing Composition 5B (invention) contained 0.02 wt. % of anaminophosphonic acid, 0.13 wt. % of tetramethylammonium hydroxide, 0.7wt. % of potassium bicarbonate, 0.04 wt. % of potassium hydroxide, 0.022wt. % of lactic acid, and 0.67 wt. % of a wet-process silica.

After misting, the compositions were allowed to dry. PolishingComposition 5A left a gelled residue. Polishing Composition 5B left adry, white residue.

Example 6

This example demonstrates silicon removal rates achievable by theinventive polishing composition.

Two separate silicon substrates were polished with two differentpolishing compositions (Polishing Compositions 6A and 6B). PolishingCompositions 6A and 6B contained 0.02 wt. % of an aminophosphonic acid,0.13 wt. % of tetramethylammonium hydroxide, 0.7 wt. % of potassiumbicarbonate, 0.04 wt. % of potassium hydroxide, and 0.022 wt. % oflactic acid. Polishing Composition GA further contained 10.0 wt. % of awet-process silica, namely, Nalco DVSTS006. Polishing Composition 6Bfurther contained 10.0 wt. % of a different wet-process silica, namely,Nalco TX11005.

Following polishing, the removal rates for silicon were determined in mgof silicon removed per minute of polishing. Polishing Composition 6Aexhibited a silicon removal rate of 13.5 mg Si/min. PolishingComposition GB exhibited a silicon removal rate of 14.2 mg Si/min.

Example 7

This example demonstrates silicon removal rates achievable by theinventive polishing composition.

Two separate silicon substrates were polished with two differentpolishing compositions (Polishing Compositions 7A and 7B). PolishingComposition 7A contained 0.004 wt. % of an aminophosphonic acid, 0.027wt. % tetramethylammonium hydroxide, 0.007 wt. % potassium bicarbonate,0.08 wt. % potassium hydroxide, 0.013 wt. % lactic acid, and 1.2 wt. %fumed silica. Polishing Composition 7B contained 0.004 wt. % of anaminophosphonic acid, 0.053 wt. % tetramethylammonium hydroxide, 0.013wt. % potassium bicarbonate, 0.08 wt. % potassium hydroxide, 0.027 wt. %lactic acid, and 1.2 wt. % fumed silica.

Following polishing, the removal rates for silicon were determined in mgof silicon removed per minute of polishing. Polishing Composition 7Aexhibited a silicon removal rate of 11.2 mg Si/min. PolishingComposition 7B exhibited a silicon removal rate of 11.8 mg Si/min.

Example 8

This example demonstrates silicon oxide removal rates achievable by theinventive polishing composition.

Two separate silicon oxide substrates were polished with two differentpolishing compositions (Polishing Compositions 8A and 8B). The siliconoxide was derived from tetraethylorthosilicate. Polishing Composition 8Acontained 0.015 wt. % of an aminophosphonic acid, 0.1 wt. %tetramethylammonium hydroxide, 0.025 wt. % potassium bicarbonate, 0.3wt. % potassium hydroxide, 0.05 wt. % lactic acid, and 4.4 wt. % fumedsilica. Polishing Composition 8B contained 0.015 wt. % of anaminophosphonic acid, 0.2 wt. % tetramethylammonium hydroxide, 0.05 wt.% potassium bicarbonate, 0.3 wt. % potassium hydroxide, 0.1 wt. % lacticacid, and 4.3 wt. % fumed silica.

Following polishing, the removal rates for silicon oxide were determinedin mg of silicon removed per minute of polishing. Polishing Composition8A exhibited a silicon oxide removal rate of 2.7 mg SiO/min. PolishingComposition 8B exhibited a silicon oxide removal rate of 4.9 mg SiO/min.

All references, including publications, patent applications, andpatents, cited herein are hereby incorporated by reference to the sameextent as if each reference were individually and specifically indicatedto be incorporated by reference and were set forth in its entiretyherein.

The use of the terms “a” and “an” and “the” and similar referents in thecontext of describing the invention (especially in the context of thefollowing claims) are to be construed to cover both the singular and theplural, unless otherwise indicated herein or clearly contradicted bycontext. The terms “comprising,” “having,” “including,” and “containing”are to be construed as open-ended terms (i.e., meaning “including, butnot limited to,”) unless otherwise noted. Recitation of ranges of valuesherein are merely intended to serve as a shorthand method of referringindividually to each separate value falling within the range, unlessotherwise indicated herein, and each separate value is incorporated intothe specification as if it were individually recited herein. All methodsdescribed herein can be performed in any suitable order unless otherwiseindicated herein or otherwise clearly contradicted by context. The useof any and all examples, or exemplary language (e.g., “such as”)provided herein, is intended merely to better illuminate the inventionand does not pose a limitation on the scope of the invention unlessotherwise claimed. No language in the specification should be construedas indicating any non-claimed element as essential to the practice ofthe invention.

Preferred embodiments of this invention are described herein, includingthe best mode known to the inventors for carrying out the invention.Variations of those preferred embodiments may become apparent to thoseof ordinary skill in the art upon reading the foregoing description. Theinventors expect skilled artisans to employ such variations asappropriate, and the inventors intend for the invention to be practicedotherwise than as specifically described herein. Accordingly, thisinvention includes all modifications and equivalents of the subjectmatter recited in the claims appended hereto as permitted by applicablelaw. Moreover, any combination of the above-described elements in allpossible variations thereof is encompassed by the invention unlessotherwise indicated herein or otherwise clearly contradicted by context.

1. A method for polishing an edge of a silicon wafer, wherein the edgeconsists essentially of silicon, which method comprises: (i) contactinga substrate with a polishing pad and a chemical-mechanical polishingcomposition consisting essentially of: (a) about 0.5 wt. % to about 20wt. % of wet-process silica, (b) about 0.01 wt. % to about 5 wt. % of anorganic carboxylic acid, (c) about 0.0005 wt. % to about 2 wt. % of anaminophosphonic acid, (d) about 0.01 wt. % to about 5 wt. % of atetraalkylammonium salt, (e) potassium hydroxide, (F) optionally abicarbonate salt, and (g) water, wherein the polishing composition has apH of about 7 to about 11, (ii) moving the polishing pad relative to theedge of the silicon wafer with the chemical-mechanical polishingcomposition therebetween, and (iii) abrading at least a portion of theedge to polish the edge of the silicon wafer.
 2. The method of claim 1,wherein the polishing composition contains about 0.02 wt. % to about 5wt. % of an organic carboxylic acid, about 0.02 wt. % to about 2 wt. %of an aminophosphonic acid, and about 0.1 wt. % to about 5 wt. % of atetraalkylammonium salt.
 3. The method of claim 2, wherein the polishingcomposition contains about 5 wt. % to about 20 wt. % of wet-processsilica.
 4. The method of claim 3, wherein the polishing compositioncontains about 10 wt. % to about 15 wt. % of wet-process silica.
 5. Themethod of claim 2, wherein the wet-process silica has an averageparticle size of about 4 nm to about 180 nm.
 6. The method of claim 5,wherein the wet-process silica has an average particle size of about 20nm to about 50 nm.
 7. The method of claim 2, wherein the polishingcomposition contains about 0.1 wt. % to about 2 wt. % of the organiccarboxylic acid.
 8. The method of claim 7, wherein the organiccarboxylic acid is a hydroxycarboxylic acid.
 9. The method of claim 8,wherein the organic carboxylic acid is selected from the groupconsisting of lactic acid, oxalic acid, 2-hydroxybutyric acid, benzilicacid, and combinations thereof.
 10. The method of claim 2, wherein thepolishing composition contains about 0.1 wt. % to about 1 wt. % of theaminophosphonic acid.
 11. The method of claim 10, wherein theaminophosphonic acid is selected from the group consisting ofethylenediaminetetra(methylene phosphonic acid), amino tri(methylenephosphonic acid), diethylenetriaminepenta(methylene phosphonic acid),and combinations thereof.
 12. The method of claim 11, wherein theaminophosphonic acid is amino tri(methylene phosphonic acid).
 13. Themethod of claim 2, wherein the polishing composition contains abicarbonate salt, and the bicarbonate salt is potassium bicarbonate. 14.The method of claim 2, wherein the polishing composition has a pH ofabout 8 to about
 10. 15. The method of claim 1, wherein the polishingcomposition consists essentially of: (a) about 0.5 wt. % to about 20 wt.% of wet-process silica, (b) about 0.01 wt. % to about 5 wt. % of anorganic carboxylic acid selected from the group consisting of lacticacid, oxalic acid, 2-hydroxybutyric acid, benzilic acid, andcombinations thereof, (c) about 0.0005 wt. % to about 2 wt. % of anaminophosphonic acid selected from the group consisting ofethylenediaminetetra(methylene phosphonic acid), amino tri(methylenephosphonic acid), diethylenetriaminepenta(methylene phosphonic acid),and combinations thereof, (d) about 0.01 wt. % to about 5 wt. % of atetraalkylammonium hydroxide, (e) about 0.05 wt. % to about 2 wt. % ofpotassium hydroxide, (f) about 0.05 wt. % to about 5 wt. % of potassiumbicarbonate, and (g) water.
 16. A method for polishing an edge of awafer, wherein the edge has a surface consisting essentially of siliconand silicon oxide, which method comprises: (i) contacting a substratewith a polishing pad and a chemical-mechanical polishing compositionconsisting essentially of: (a) about 0.5 wt. % to about 20 wt. % ofsilica, (b) about 0.01 wt. % to about 5 wt. % of an organic carboxylicacid, (c) about 0.0005 wt. % to about 1 wt. % of an aminophosphonicacid, (d) about 0.01 wt. % to about 5 wt. % of a tetraalkylammoniumsalt, (e) optionally a bicarbonate salt, (f) optionally potassiumhydroxide, and (g) water, wherein the polishing composition has a pH ofabout 7 to about 11, (ii) moving the polishing pad relative to the edgeof the wafer with the chemical-mechanical polishing compositiontherebetween, and (iii) abrading at least a portion of the edge topolish the edge of the wafer.
 17. The method of claim 16, wherein thepolishing composition contains about 0.02 wt. % to about 5 wt. % of anorganic carboxylic acid, about 0.02 wt. % to about 2 wt. % of anaminophosphonic acid, and about 0.1 wt. % to about 5 wt. % of atetraalkylammonium salt.
 18. The method of claim 17, wherein the silicais fumed silica.
 19. The method of claim 17, wherein the polishingcomposition contains about 5 wt. % to about 20 wt. % of silica.
 20. Themethod of claim 19, wherein the polishing composition contains about 10wt. % to about 15 wt. % of silica.
 21. The method of claim 17, whereinthe silica has an average particle size of about 4 nm to about 180 nm.22. The method of claim 21, wherein the silica has an average particlesize of about 20 nm to about 50 nm.
 23. The method of claim 17, whereinthe polishing composition contains about 0.1 wt. % to about 2 wt. % ofthe organic carboxylic acid.
 24. The method of claim 23, wherein theorganic carboxylic acid is a hydroxycarboxylic acid.
 25. The method ofclaim 24, wherein the organic carboxylic acid is selected from the groupconsisting of lactic acid, oxalic acid, 2-hydroxybutyric acid, benzilicacid, and combinations thereof.
 26. The method of claim 17, wherein thepolishing composition contains about 0.1 wt. % to about 1 wt. % of theaminophosphonic acid.
 27. The method of claim 26, wherein theaminophosphonic acid is selected from the group consisting ofethylenediaminetetra(methylene phosphonic acid), amino tri(methylenephosphonic acid), diethylenetriaminepenta(methylene phosphonic acid),and combinations thereof.
 28. The method of claim 27, wherein theaminophosphonic acid is amino tri(methylene phosphonic acid).
 29. Themethod of claim 17, wherein the polishing composition contains abicarbonate salt, and the bicarbonate salt is potassium bicarbonate. 30.The method of claim 17, wherein the polishing composition containspotassium hydroxide.
 31. The method of claim 17, wherein the polishingcomposition has a pH of about 8 to about
 10. 32. The method of claim 16,wherein the polishing composition consists essentially of: (a) about 0.5wt. % to about 20 wt. % of wet-process silica, (b) about 0.01 wt. % toabout 5 wt. % of an organic carboxylic acid selected from the groupconsisting of lactic acid, oxalic acid, 2-hydroxybutyric acid, benzilicacid, and combinations thereof, (c) about 0.0005 wt. % to about 2 wt. %of an aminophosphonic acid selected from the group consisting ofethylendiaminetetra(methylene phosphonic acid), amino tri(methylenephosphonic acid), diethylenetriaminepenta(methylene phosphonic acid),and combinations thereof, (d) about 0.01 wt. % to about 5 wt. % of atetraalkylammonium hydroxide, (e) about 0.05 wt. % to about 2 wt. % ofpotassium hydroxide, (f) about 0.05 wt. % to about 5 wt. % of potassiumbicarbonate, and (g) water.